The present research is concerned with studies on the interactions between gonococci and various eukaryotic cells including tissue culture, buccal mucosal, and human white blood cells. In addition, the genetic principles bearing on determination of the surface characteristics of gonococci is also being investigated. It is understanding the pathogenesis of gonorrhea and the focus of killing of gonococci by human leukocytes, modification of attachment of gonocci to leukocytes and tissue culture cells by proteolytic enzymes or by antisera against gonococci, and phenotypic changes from type 2 to type 4 to type 4* in gonococcal cclony types and biological reactivities.